The pilot departed on a cross-country flight in his experimental, amateur-built Zenair 601XL, which was equipped with an electronic ignition system.
He did not detect any electrical system anomalies before departure, but, about 14 minutes into the flight, the avionics switched to internal battery power.
The pilot was unable to troubleshoot the electrical system, and about two minutes later the engine experienced a total loss of power.
During the subsequent forced landing to a road near Hempstead, Texas, the airplane’s left wing hit a road sign, resulting in substantial damage.
The pilot conducted a post-accident examination of the airplane and found a loose connection at the generator regulator output. This eventually led to the total loss of electrical power and a subsequent loss of engine power.
Probable cause: A loose output connection from the generator voltage regulator, which resulted in a loss of power to the electronic ignition system, a total loss of engine power, and a subsequent forced landing, during which the airplane impacted a sign pole.
NTSB Identification: CEN16LA167
This April 2016 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Well yes, actually I do. I also have experience with Corvair and VW aero-conversions, and with certificated engines as well. My EAA membership number has five digits in it, and I have been driven around Oshkosh in Red One by the late Paul Poberezny himself. So yes, I have a little experience with these things. I also have a background in aircraft and automotive electrical systems.
I am also NOT the guy who crashed his airplane because the duct tape holding the wires onto the tractor alternator (which Deere doesn’t even make) fell off.
Building an airplane is a great thing, and is to be admired. But remember, the larger the island of knowledge, the longer the shoreline of ignorance. You have to know what you don’t know, and you have to be honest enough to ask for help, or at the very least, ask for a second opinion.
Crimp connectors are very frequently mis-used. People get the cheap, stiff ones from Wal-Mart and squeeze them with a $5 crimping tool from Harbor Freight. That’s not the way . . .
A large part of the EAA is education. I don’t know if this guy was in a rush to get finished, or if he didn’t think connectors were important, or what, but he paid a high price, and it easily could have been higher.
And you’re right about Chinese electrical components.
Took a look at the “diagram” . . . I wouldn’t wire a wheelbarrow from that. And yes, the location of the ammeter and shunt is totally incorrect. I also note the liberal use of “John Deere” components and part numbers.
If the rest of the airplane was built to the same “high standards” of the electrical “system”, this guy is lucky to be alive.
Question – did ANYBODY look at this before the guy yelled “clear!”?
The use of the John Deere alternator and voltage regulator is commonly used on aircraft powered by Corvair flight motors where they work very well. And there are plenty of those installations to back up that claim. That combination performs well in such an instance where the electrical load is low and within the units 20 amp rating. The only weak link is the voltage regulator for which it can be difficult to find a well made reliable component, most on the market are just Chinese crap. Your highlighting of this as a concern is a clear reflection of your lack of knowledge in this area. Do you have any actual experience with building aircraft in the EAB category? Most of the comments I have seen reflect a lack of understanding of what the FAA/DAR inspection is all about and it is NOT a design review, more a check of acceptable workmanship. If the builder makes the material choices as was done in this case that is more a design issue. The push on spade terminals are completely acceptable so long as they are installed with care. Yes the wiring diagram is disgraceful but that is on the designer/builder.
The electrical wiring diagram shown in the docket is a total mess.!! The ammeter shunt is NEVER put in the ground wire of the battery. This causes the starter current of 200-300 amps to go through the shunt and will destroy it, besides the 5-6 volts lost in the drop across the shunt..
The other wiring does not follow any accepted convention.
see the docket; https://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=59070&CFID=1898863&CFTOKEN=9c35b9312cb64557-E3B5F0F2-0FB9-0268-B336EE03AC467EA7
The accepted practice for retaining ‘push on’ terminals is to rill an .040 hole through the terminal and secure it with a safety wire.
This aircraft should have not been approved for flight.
Just for the sake of argument the push on connectors are used a good bit in the EAB aircraft world and they give good service there as they do in all other forms of transportation. I have never personally seen such a practice of drilling a hole for safety wire (what do you tie a Hot connector to?) nor have I seen it recommended by any knowledgeable source. The use of such connectors in no way made this aircraft (or hundreds others) unfit for flight. That has a caveat that you use good quality connectors and use good judgement in the installation. Having looked at the picture of the voltage regulator I would say that some of the connectors, especially the one that came loose, look like they came from a discount autoparts supply. You put the good quality connector on the wire (hopefully acft grade) with the correct type of crimping pliers and ensure that you have a good friction fit to the terminal.
The so called Electrical System diagram looks like nothing more than a scribbling on the back of a napkin from an early design stage. And the lack of any effective warning for the loss of the alternator in an aircraft with an engine that requires power for the ignition was a very poor bit of aircraft building in my educated opinion. Knowing that you have a functioning charging system is one of the more critical bits of engine instrumentation in such an installation. From the pilots comments he figured out there was a problem when the electronic instruments reverted to their internal batteries and that was way to late for such a discovery.
Overall a lot of bad judgement and bad decisions but he survived so maybe he learned something from it.
Sarah, you are 110% correct!
Sorry, the state of the electrical system, if as designed from the sketch, makes this aircraft un-airworthy and should have never been approved for flight.
So the ammeter shunt is badly located and MIGHT be grounds for failing the FAA/DAR inspection. Going beyond that the rest appears to be representative of many other systems that work very well in service. Yes it is a poor sketch but the details look to reflect a proper design, it is just up to the builder/designer to use the best quality materials available in executing it. This person did make a bad choice in a couple of the connectors to the voltage regulator as they appear to be just the cheap hardware store variety, but at least one looks to be the preferred AMP brand.
An image of the voltage regulator is in the NTSB Docket for this non-fatal accident. The regulator has five (5) clip wires with connectors feeding from it to the essential aircraft systems. NONE of the connectors have keepers that would resist unplanned in flight disconnection. All are cheap compression connectors that slide over spade type mounts on the regulator. The connector that came loose didn’t look like it had been compressed much. It reminded me of a fatal RV accident (see the docket and NTSB report for “Trish’s Ride Home”) that suffered a similar inconvenient loss of power.